The present invention relates generally to a system and method for operating and dimming lighting devices. More particularly, the present invention relates to a microcontroller and associated circuitry for individually controlling the lighting intensity of different color LEDs in a lighting device.
Pulse width modulated (PWM) output signals are commonly used to control the intensity of light-emitting elements in lighting devices. Separate PWM output signals may be provided to individual elements, or to a number of such elements in an array. Typically, timer peripherals contained within a microcontroller or an equivalent are configured to generate such signals with the quality and quantity of available outputs being determined by the design of the timer hardware. Hardware timers allow signals to be generated with little intervention from a central processor, but they also add complexity and cost to the microcontroller.
Timers having multiple output PWM output capability are further generally unavailable in the lowest cost microcontrollers. For example, conventional microcontrollers (such as for example a microcontroller 112 as shown in FIG. 7) which might be used for such a system generally include either three pulse-width modulation (PWM) timers or a single timer with three PWM channels (R, G, B). This can be particularly disadvantageous for the example of an RGB (Red, Green, Blue) LED (Light-Emitting Diode) array, where multiple PWM outputs would be desirable to individually modulate the relative light intensities associated with the various LED colors.